Signaling system for railroads



Jan. 18, 1938. w, RE|CHARD 2,105,930 I SIGNALING SYSTEM FOR RAILROADS Fiied Jan. 22, 1935 Patented Jan. 18, 1938 UNITED STATES PATENT OFFICE Wade H. Reichard, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application January 22, 1935, Serial No. 2,896

4 Claims.

This invention relates to means for detecting the presence of railway vehicles or trains at any point in extending portions of the track for the purpose of controlling block signals, cab signals, or automatic train control devices, or the like.

In the art of railway signaling in general, the well-known normally energized track circuit is usually employed for detecting the presence of a vehicle or train at any point in a given track section or block. Under some special and exceptional conditions, such as where the ballast conditions are poor and widely variable, or the vehicles have uncertain and variable shunting effect, the ordinary track circuit may fail to give the desired unfailing and desirable operation at all times. Also, there may be cases Where the usual track circuit cannot be advantageously used, as for example, in connection with car retarders, around switches and crossovers, and the like; and in such cases is desirable to employ a means as a substitute for, or perhaps in addition to, the usual track circuits for detecting the presence of cars.

With these and other considerations in mind, it is proposed in accordance with this invention, generally speaking, to provide a wayside circuit, separate from the track rails but extending along the track for corresponding track section distances, said circuit being influenced by the presence of a railway car or vehicle in such a way as to operate a suitable electro-responsive means. More specifically, it is proposed to provide a tuned wayside circuit which normally maintains a relay energized and which is inductively influenced more particularly by a detuning action, by the presence of a vehicle to the extent that the relay is de-energized.

Various characteristic features, attributes and functions of the invention will be in part apparent and in part explained as the description progresses.

The accompanying drawing illustrates in a simplified and diagrammatic manner one specific embodiment of the invention, such illustration being intended to facilitate an understanding of the nature of the invention, rather than to show the physical structures that would be employed in practice.

It is contemplated that the car detecting means of this invention may be used in connection with, or as a substitute for, the usual track circuit; and while shown in connection with a conventional normally energized track circuit, it should be understood that the organization of this invention may be used by itself.

Referring to the drawing, the track rails l are bonded together in the usual way and divided into blocks or track sections by insulated joints 2, the equipment being shown for one track section A, which is typical of all others. At one end of the track section, preferably at the exit end (trafi'lc being from left to right as indicated by the arrow), a source of track circuit current, shown as a battery 3, is connected across the track rails in series with the usual limiting resistance 4, in accordance with common practice; and at the other end of the track section, the usual track relay T is connected across the track rails. This track circuit operates in the wellknown manner.

Considering the parts relating to the present invention, the wayside circuit comprises track wires 5, in the form of a loop suitably supported and insulated and extending parallel to the track rails throughout the length of the track section *3 A, preferably between the track rails. This wayside circuit includes a condenser 6 near the exit end of the track section; and at the other end of the track section the wayside circuit includes the primary of a transformer l, which has its secondary connected through a double wave rectifier 8 of the usual construction to a suitable sensitive electro-responsive device or relay 9.

This wayside circuit is energized with alternating current, preferably of a relatively high frequency such as 300 cycles; and in the particular arrangement shown, this is accomplished by including in the circuit the secondary of a transformer ill, the primary of which is energized with alternating current of the desired frequency by an oscillating vacuum tube organization of the usual type and construction indicated at ll. Any suitable high frequency generator may be employed; and the wayside circuit may be energized from a transmission line.

This wayside circuit is tuned by the condenser 6, with due regard to the capacity between the track wires 5 and the reactance in the circuit, so as to be resonant when no car or vehicle is present at any point in the track section.

When a railway vehicle enters the track section, or is present at any point in its length, this vehicle will inductively influence the track wires 5, for a portion of their length, and change the electrical characteristics of the Wayside circuit sufficiently to reduce the current through the relay 9 and cause it to release its armature. The effect of the car on the wayside circuit is considered to be principally a detuning action due to the change in linear impedance or effective resistance in the circuit produced by the presence of the magnetic and metallic masses constituting the car.

It appears that the effect on the wayside circuit produced by the presence of a car may be increased by providing on the car a loop or coil I2 disposed to have maximum coupling with the track wires 5 and 5, and tuned by a condenser I3 to be substantially resonant at the frequency of the current energizing the wayside circuit. It is believed that such tuned loop H. on the car produces in the wayside circuit the effect of additional resistance or capacity in the track wires 5 in such a way as to materially change the current in the wayside circuit by the action of detuning and including additional reactance. It is contemplated that the car-carried loop [2 will be constructed, supported and suitably housed in such a way that its integrity is assured.

Since the wayside circuit, and electro-responsive device on the relay 9 controlled thereby, are normally energized, any failure of power or breakage of wires will cause deenergization of the relay and constitute a failure on the side of safety. In this connection, the condenser 6 is located at the end of the trackway circuit or loop, at the exit end of the block, so that crosses, grounds, and breaking of the track wires 5 at intermediate points will cause de-energization of the relay 9.

It is contemplated that the sensitivity of the trackway circuit is such that the track wires 5 can be extended throughout the length of the ordinary track section, and that the inductive influence or effect of a single railway vehicle at any point on the track section will produce a sufficient change in the electrical characteristics of the wayside circuit to de-energize the relay 53. It is evident, however, that the track wires may be extended for a shorter distance along the track than the usual track section, and that two or more track circuits or loops may be employed for every portion of track representing a track circuit section or block.

The electro-responsive device or relay 9 may be utilized to control wayside signals, or a cab signal or train control system, in the same way as a track relay, all in a manner which will be readily apparent to those skilled in the art. If the car detecting means of this invention is employed in conjunction with the usual track circuit, the controlling circuit of the Wayside signals or the like is arranged to include contacts of both the track relay T and relay 9, as shown conventionally.

The car detecting means of the invention is adapted for various applications and uses; and various adaptations, modifications, and additions may be made in the particular construction and arrangement of parts shown and described, without departing from the invention.

What I claim is:-

1. In a signaling system for railroads, the combination with a normally energized track circuit, of a wayside circuit including insulated track Wires extending along the track parallel with the track rails which constitutes part of the track circuit, means for energizing said wayside circuit with alternating current, said wayside circuit being resonant at the frequency of said current, electro-responsive means controlled by the current in said wayside circuit, vehicle means controlling the wayside circuit and means for signaling controlled jointly by said track circuit and said electro-responsive means.

2. A system for detecting the presence of a railway vehicle at any point in an extended portion of track comprising, a wayside circuit including track wires separate from the track rails and extending along the said portion of track, means for energizing said circuit at one end with current of a relatively high frequency, a condenser at the other end of said circuit tuning it to resonance at said frequency when said track is free of railway vehicles, and electro-rcsponsive means normally maintained inactive while said wayside circuit is resonant and eifectively deenergized when the resonance of said wayside circuit is disturbed by the presence of a vehicle on said portion of track.

3. In a system of the character described, the combination, with a trackway, of a track circuit including a track relay, a resonant wayside circuit including track wires extending along the track parallel with the track rails and the track circuit and energized with alternating current, a wayside signal control circuit normally controlled by said resonant circuit and said track circuit, and a tun-ed loop on a vehicle movable over the trackway and having substantially maximum coupling with said track wires.

4. In a signaling system for railroads, the combination with a normally energized track circuit, of a wayside circuit including insulated track Wires extending along the track parallel with the track rails which constitutes part of the track circuit, means for energizing said wayside circuit with alternating current, said wayside circuit being resonant at the frequency of said current, electro-responsive means controlled by the current in said wayside circuit, vehicle carried means inductively coupled with said wayside circuit during the presence of the vehicle on said track circuit for controlling the wayside circuit, and rail- Way signaling means controlled jointly by said track circuit and said electro-responsive means.

WADE H. REICHARD. 

